There may be no single cause of bipolar disorder (aka manic depression). Instead, research indicates the causes of bipolar disorder are probably a combination of biochemical, genetic and environmental factors that may trigger and perpetuate the chemical imbalances in the brain.
Net worth: $829 million. Telecommunications mogul Strive Masiyiwa is widely regarded as the richest man in Zimbabwe and is one of the richest men in Africa with a net worth of more than US$800 million.
Great Zimbabwe is an archaeological site which is a very important heritage resource in southern Africa. The name of the country of Zimbabwe is even based on the Shona term dzimba dzembabwe, meaning 'house of stone'. The ruins of Great Zimbabwe provide evidence of an early and sophisticated civilisation.